<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="https://unpkg.com/vue@3/dist/vue.global.js"></script>
</head>
<body>

  <div id="app">
{{reverseMsg}}
  </div>

  <script>
  const { createApp , ref, computed }  = Vue;
  const app = createApp({
    setup(){

        const msg = ref('今天的天气');
        const reverseMsg = computed(() => {
            return msg.value.split('').reverse().join('')
        })

        return {
            msg,
            reverseMsg
        }
    }
  });


  app.mount('#app');

  </script>

</body>
</html>